Characterization and application of a channel-planar composite waveguide

A new structural waveguide, which is referred to as a channel-planar composite optical waveguide (COWG), has been fabricated by sputtering of a titanium dioxide (TiO2) film onto a glass substrate with potassium ion-exchanged channel waveguides. By use of a mask during deposition, the TiO2 film was formed into a 27-nm-thick, 5-mm-wide strip with two 1-mm-long tapered ends perpendicular to the channel waveguides. Adiabatic transition of the TE00 mode and the TE00-TM00 mode separation inside such a channel-planar COWG were demonstrated by combination of theoretical analysis and measurement of the experimental attenuation that arises from scattering loss and evanescent-field dye absorption. Changing the superstrate index in the region of the TiO2 film in the channel-planar COWG yielded polarimetric interference patterns. This new technique can be applied to integrated optical chemical and biological sensors to produce enhanced sensitivity. (C) 2000 Optical Society of America.